Recovery of zinc from iron-making or steel-refining furnace dust

Abstract

The zinc-containing dust from an iron-making (blast) furnace or a steel-refining (e.g. converter) furnace is recovered and extracted with water saturated with carbon dioxide to solubilize the zinc. The zinc solubilized in the CO 2 -saturated water is then precipitated by the elimination of carbon dioxide therefrom.

We claim: 
     
       1. A process for recovery of zinc from the dust of a metallurgical plant which comprises the steps of: a. forming compacts of said dust;   b. saturating water with carbon dioxide; to form a treating solution;   c. treating the compacts of said dust with said water saturated with carbon dioxide for a period and at a temperature sufficient at a pressure of the order of 15 to 40 kg/cm 2  to solubilize zinc from the dust compacts in the water of the treating solution; and   d. precipitating the zinc from said solution by eliminating carbon dioxide therefrom.   
     
     
       2. The process defined in claim 1 wherein the treating solution is saturated with carbon dioxide by solubilizing therein carbon dioxide from the gas of a metallurgical plant therein. 
     
     
       3. The process defined in claim 1 wherein said treating solution contains sulfur dioxide. 
     
     
       4. The process defined in claim 1, further comprising the step of adding a mineral acid to the treating solution used to treat said dust. 
     
     
       5. The process defined in claim 1 wherein said pressure is of the order of 30 kg/cm 2 . 
     
     
       6. The process defined in claim 1 wherein the zinc is precipitated from said solution by aeration thereof. 
     
     
       7. The process defined in claim 1 wherein the zinc is separated from said solution by heating said solution to drive the carbon dioxide therefrom. 
     
     
       8. The process defined in claim 1 wherein the zinc is precipitated from said solution by subjecting said solution to vacuum to drive carbon dioxide therefrom. 
     
     
       9. The process defined in claim 1, further comprising the step of adding an alkaline substance to said solution for precipitation of zinc therefrom.